Methods for Increasing RF Throughput Via Usage of Tunable Filters

ABSTRACT

Methods and devices are described for increasing RF throughput in a multiple RF paths RF transmit/receive system with a plurality RF transmit/receive systems. In one case a tunable notch filter is used to reduce channel interference between the plurality of RF transmit/receive systems.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.______ entitled “Devices and Methods for Duplexer Loss Reduction”(Attorney Docket No. PER-100-PAP) filed on even date herewith andincorporated herein by reference in its entirety. The presentapplication is also related to U.S. patent application Ser. No. ______entitled “Integrated Tunable Filter Architecture” (Attorney Docket No.PER-115-PAP) filed on even date herewith and incorporated herein byreference in its entirety.

The present application may be related to U.S. Pat. No. 6,804,502,issued on Oct. 12, 2004 and entitled “Switch Circuit and Method ofSwitching Radio Frequency Signals”, the disclosure of which isincorporated herein by reference in its entirety. The presentapplication may also be related to U.S. Pat. No. 7,910,993, issued onMar. 22, 2011 and entitled “Method and Apparatus for use in improvingLinearity of MOSFET's using an Accumulated Charge Sink”, the disclosureof which is incorporated herein by reference in its entirety. Thepresent application may also be related to U.S. patent application Ser.No. 13/797,779 entitled “Scalable Periphery Tunable Matching PowerAmplifier”, filed on Mar. 3, 2013, the disclosure of which isincorporated herein by reference in its entirety. The presentapplication may also be related to International Application No.PCT/US2009/001358, entitled “Method and Apparatus for use in digitallytuning a capacitor in an integrated circuit device”, filed on Mar. 2,2009, the disclosure of which is incorporated herein by reference in itsentirety. The present application may also be related to U.S. patentapplication Ser. No. 13/595,893, entitled “Method and Apparatus for Usein Tuning Reactance in a Circuit Device”, filed on Aug. 27, 2012, thedisclosure of which is incorporated herein by reference in its entirety.The present application may also be related to U.S. patent applicationSer. No. 14/042,312, filed on Sep. 30, 2013, entitled “Methods andDevices for Impedance Matching in Power Amplifier Circuits”, thedisclosure of which is incorporated herein by reference in its entirety.The present application may also be related to U.S. Pat. No. 7,248,120,issued on Jul. 24, 2007, entitled “Stacked Transistor Method andApparatus”, the disclosure of which is incorporated herein by referencein its entirety. The present application may also be related to U.S.patent application Ser. No. 13/828,121, filed on Mar. 14, 2013, entitled“Autonomous Power Amplifier Optimization”, the disclosure of which isincorporated herein by reference in its entirety. The presentapplication may also be related to U.S. patent application Ser. No.13/967,866 entitled “Tunable Impedance Matching Network”, filed on Aug.15, 2013, the disclosure of which is incorporated herein by reference inits entirety. The present application may also be related to U.S. patentapplication Ser. No. 13/797,686 entitled “Variable Impedance Match andVariable Harmonic Terminations for Different Modes and Frequency Bands”,filed on Mar. 12, 2013, the disclosure of which is incorporated hereinby reference in its entirety. The present application may also berelated to U.S. patent application Ser. No. 14/042,331 entitled “Methodsand Devices for Thermal Control in Power Amplifier Circuits”, filed onSep. 30, 2013, the disclosure of which is incorporated herein byreference in its entirety. The present application may also be relatedto U.S. patent application Ser. No. 13/829,946 entitled “AmplifierDynamic Bias Adjustment for Envelope Tracking, filed on Mar. 14, 2013,the disclosure of which is incorporated herein by reference in itsentirety. The present application may also be related to U.S. patentapplication Ser. No. 13/830,555 entitled “Control Systems and Methodsfor Power Amplifiers Operating in Envelope Tracking Mode”, filed on Mar.14, 2013, the disclosure of which is incorporated herein in itsentirety.

BACKGROUND

1. Field

The present teachings relate to RF (radio frequency) circuits. Moreparticularly, the present teachings relate to methods for increasingdata throughput in an RF transmit/receive system.

2. Description of Related Art

Radio frequency (RF) devices, such as cell phone transmitters, arebecoming increasingly complex due to additional frequency bands, morecomplex modulation schemes, higher modulation bandwidths, and theintroduction of data throughput improvement schemes such as simultaneousRF transmission and/or reception within a same or different, but closelyspaced, bands or channels within a band (e.g. voice, data), andaggregate transmission wherein information is multiplexed over parallelRF transmissions. Due to the high integration and closely spacedtransmit/receive paths of a front-end stage used in such RF devices, RFsignal interference from neighboring paths, either receive or transmit,can influence RF signal of a transmit/receive path (e.g. viaintermodulation) and therefore affect (e.g. reduce) a correspondingthroughput by increasing spectrum usage within a frequency band andtherefore limiting the number of simultaneous RF transmission and/orreception (e.g. number of usable channels) within a frequency band.

SUMMARY

According to a first aspect of the present disclosure, a radio frequency(RF) circuital arrangement is presented, the arrangement comprising: afirst transmit/receive system comprising a first transmit pathconfigured to transmit a first transmit RF signal at a firsttransmit/receive port, and a first receive path configured to receive afirst receive RF signal at the first transmit/receive port; a secondtransmit/receive system comprising a second transmit path configured totransmit a second transmit RF signal at a second transmit/receive port,and a second receive path configured to receive a second receive RFsignal at the second transmit/receive port, and one or more tunablenotch filters configured to reduce a radio frequency interference of atransmit/receive system of the first and second transmit/receive systemsover the other transmit/receive system.

According to second aspect of the present disclosure, a radio frequency(RF) integrated circuit is presented, the integrated circuit comprising:an RF switch comprising a first switch terminal and a second switchterminal; a RF tunable notch filter comprising a first port and a secondport, wherein in a first configuration of the RF integrated circuit thefirst port is connected to the first switch terminal and the second portis connected to the second switch terminal, and in a secondconfiguration of the RF integrated circuit the first port is connectedto the second switch terminal; a first input/output terminal connectedto the first switch terminal; a second input/output terminal connectedto the second port, and a control terminal, wherein during operation, acontrol signal at the control terminal of the RF integrated circuit isconfigured to tune the RF tunable notch filter and/or control the RFswitch to enable/disable a current flow through the RF tunable notchfilter.

According to a third aspect of the present disclosure, a method forreducing radio frequency (RF) interference in an RF circuitalarrangement is presented, the method comprising: providing a pluralityof RF transmit/receive systems coupled to a plurality RF antennas;connecting in a path of a first RF transmit/receive system of theplurality of RF transmit/receive systems one or more RF tunable notchfilters; adjusting an RF tunable notch filter of the one or more RFtunable notch filters based on a characteristic of a transmit/receive RFsignal of an RF transmit/receive system of the plurality of RFtransmit/receive systems other than the first RF transmit/receivesystem, and based on the adjusting, reducing an RF interference of thetransmit/receive RF signal over the first RF transmit/receive system.

According to a fourth aspect of the present disclosure, a radiofrequency (RF) circuital arrangement is presented, the arrangementcomprising: a transmit path configured to transmit, during a transmitmode of operation of the RF circuital arrangement, a transmit RF signalat a transmit/receive port of the RF circuital arrangement; a receivepath configured to receive, during a receive mode of operation of the RFcircuital arrangement, a receive RF signal at the transmit/receive port,and a tunable notch filter configured to reduce a radio frequencyinterference of the transmit RF signal over the receive RF signal,wherein during operation, the RF circuital arrangement is configured tosimultaneously operate in the transmit and receive modes of operation.

According to a fifth aspect of the present disclosure a method forreducing radio frequency (RF) interference in an RF circuitalarrangement is presented, the method comprising: providing an RFtransmit path to transmit a transmit RF signal over an antenna;providing an RF receive path to receive a receive RF signal over theantenna; coupling a tunable notch tilter to the RF transmit or the RFreceive path; adjusting the tunable notch filter based on a frequency ofoperation of the transmit RF signal, and based on the adjusting,reducing an RF interference of the transmit RF signal over the receiveRF signal.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent disclosure and, together with the description of exampleembodiments, serve to explain the principles and implementations of thedisclosure.

FIG. 1 shows an exemplary block diagram of a transmit/receive systemcomprising a transmit path and a receive path used in a multi-band andmulti-channel RF front-end stage of an RF device, as used, for example,in a cellular phone.

FIG. 2A shows an exemplary graph of frequency spectra of an RF transmitsignal and an RF receive signal of the transmit/receive system of FIG.1.

FIG. 21 and FIG. 2C show exemplary graphs of frequency bands andassociated frequency channels which can be used in the transmit/receivesystem of FIG. 1.

FIG. 2D shows an exemplary embodiment according to the presentdisclosure of a transmit/receive system comprising a tunable notchfilter in a receive path.

FIG. 3 shows an exemplary block diagram of a multiple RF pathstransmit/receive system comprising two parallel transmit/receive systemswhich can be used to increase throughput of an RF front-end stage.

FIG. 4A shows a frequency plan which can be used by the multiple RFpaths transmit/receive system of FIG. 3.

FIG. 4B shows a frequency plan comprising intermodulation products oftwo RF signals.

FIG. 4C shows a frequency plan comprising intermodulation products oftwo RF transmit signals of the multiple RF paths transmit/receive systemof FIG. 3, wherein an intermodulation product can occupy one or morereceive channels of a receive band used by the multiple RF pathstransmit/receive system.

FIG. 4D shows the frequency plan of FIG. 4C for a case where additionalto the two RF transmissions, an RF reception is also taking place. Asdepicted in FIG. 4D, a spectrum of an intermodulation product betweenthe two RF transmit signals can occupy a portion of the spectrum usedfor an RF receive signal.

FIGS. 5A-SB show embodiments according to the present disclosure of themultiple RF paths transmit/receive system of FIG. 3, wherein a tunablenotch filter is used to reduce interference of one transmit/receivesystem over the other.

FIG. 6 shows an embodiment according to the present disclosure of themultiple RF paths transmit/receive system of FIG. 3, wherein series andshunt connected tunable notch filters within both the transmit/receivesystems are used to immune either transmit/receive system with respectto the other.

FIG. 7 shows an embodiment according to the present disclosure whereinswitches are used to bypass the series and shunt connected tunable notchfilters used in FIG. 6.

FIG. 8A shows an embodiment according to the present disclosure of amonolithically integrated tunable notch filter in parallel connectionwith an RF switch.

FIG. 8B shows an embodiment according to the present disclosure of amonolithically integrated tunable notch filter in series connection withan RF switch.

FIG. 9 shows an exemplary embodiment of a switch with stackedtransistors.

DETAILED DESCRIPTION

Throughout this description, embodiments and variations are describedfor the purpose of illustrating uses and implementations of theinventive concept. The illustrative description should be understood aspresenting examples of the inventive concept, rather than as limitingthe scope of the concept as disclosed herein.

As used in the present disclosure, the terms “switch ON” and “activate”may be used interchangeably and can refer to making a particular circuitelement electronically operational. As used in the present disclosure,the terms “switch OFF” and “deactivate” may be used interchangeably andcan refer to making a particular circuit element electronicallynon-operational. As used in the present disclosure, the terms“amplifier” and “power amplifier” may be used interchangeably and canrefer to a device that is configured to amplify a signal input to thedevice to produce an output signal of greater magnitude than themagnitude of the input signal.

The present disclosure describes electrical circuits in electronicsdevices (e.g., cell phones, radios) having a plurality of devices, suchas for example, transistors (e.g., MOSFETs). Persons skilled in the artwill appreciate that such electrical circuits comprising transistors canbe arranged as amplifiers. As described in a previous disclosure (U.S.patent application Ser. No. 13/797,779, incorporated herein by referencein its entirety), a plurality of such amplifiers can be arranged in aso-called “scalable periphery” (SP) architecture of amplifiers where atotal number (e.g., 64) of amplifier segments are provided. Depending onthe specific requirements of an application, the number of activedevices (e.g., 64, 32, etc.), or a portion of the total number ofamplifiers (e.g. 1/64, 2/64, 40% of 64, etc. . . . ), can be changed foreach application. For example, in some instances, the electronic devicemay desire to output a certain amount of power, which in turn, mayrequire 32 of 64 SP amplifier segments to be used. In yet anotherapplication of the electronic device, a lower amount of output power maybe desired, in which case, for example, only 16 of 64 SP amplifiersegments are used. According to some embodiments, the number ofamplifier segments used can be inferred by a nominal desired outputpower as a function of the maximum output power (e.g. when all thesegments are activated). For example, if 30% of the maximum output poweris desired, then a portion of the total amplifier segments correspondingto 30% of the total number of segments can be enabled. The scalableperiphery amplifier devices can be connected to corresponding impedancematching circuits. The number of amplifier segments of the scalableperiphery amplifier device that are turned on or turned off at a givenmoment can be according to a modulation applied to an input RF signal, adesired output power, a desired linearity requirement of the amplifieror any number of other requirements.

The term “amplifier” as used in the present disclosure is intended torefer to amplifiers comprising single or stacked transistors configuredas amplifiers, and can be used interchangeably with the term “poweramplifier (PA)”. Such terms can refer to a device that is configured toamplify a signal input to the device to produce an output signal ofgreater magnitude than the magnitude of the input signal. Stackedtransistor amplifiers are described for example in U.S. Pat. No.7,248,120, issued on Jul. 24, 2007, entitled “Stacked Transistor Methodand Apparatus”, the disclosure of which is incorporated herein byreference in its entirety. Such amplifier and power amplifiers can beapplicable to amplifiers and power amplifiers of any stages (e.g.,pre-driver, driver, final), known to those skilled in the art.

As used in the present disclosure, the term “mode” can refer to awireless standard and its attendant modulation and coding scheme orschemes. As different modes may require different modulation schemes,these may affect required channel bandwidth as well as affect thepeak-to-average-ratio (PAR), also referred to aspeak-to-average-power-ratio (PAPR), as well as other parameters known tothe skilled person. Examples of wireless standards include Global Systemfor Mobile Communications (GSM), code division multiple access (CDMA),Worldwide Interoperability for Microwave Access (WiMAX), Long TermEvolution (LTE), as well as other wireless standards identifiable to aperson skilled in the art. Examples of modulation and coding schemesinclude binary phase-shift keying (BPSK), quadrature phase-shift keying(QPSK), quadrature amplitude modulation (QAM), 8-QAM, 64-QAM, as well asother modulation and coding schemes identifiable to a person skilled inthe art.

As used in the present disclosure, the term “band” can refer to afrequency range. More in particular, the term “band” as used hereinrefers to a frequency range that can be defined by a wireless standardsuch as, but not limited to, wideband code division multiple access(WCDMA) and long term evolution (LTE).

As used in the present disclosure, the term “channel” can refer to afrequency range. More in particular, the term “channel” as used hereinrefers to a frequency range within a band. As such, a band can compriseseveral channels used to transmit/receive a same wireless standard.

FIG. 1 shows a block diagram of a transmit/receive system (100)comprising a transmit path and a receive path which can be used in amulti-band and multi-channel RF front-end stage of an RF device, suchas, for example, a cellular phone. The transmit/receive system (100) ofFIG. 1 comprises a transceiver unit (140) adapted to generate an RFsignal to be transmitted via an antenna (110) of the system. An RFtransmit path of the transmit/receive system (100) can comprise an RFamplifier module (120) and a duplexer unit (130). The RF amplifiermodule (120) can amplify the RF signal provided by the transceiver unit(140) and further shape the RF signal in a way more suitable fortransmission, such as described in, for example, U.S. patent applicationSer. No. 13/829,946 and U.S. patent application Ser. No. 13/830,555,both of which are herein incorporated by reference in their entirety.Furthermore, as known to the person skilled in the art, the amplifiermodule (140) can comprise a plurality of series connected amplifiers,such as a driver and a final, wherein each of the series connectedamplifiers may further comprise stacked transistors such as describedin, for example, U.S. Pat. No. 7,248,120, incorporated herein byreference in its entirety, and/or parallel amplifiers such as scalableperiphery amplifiers, as described in, for example, U.S. patentapplication Ser. No. 13/797,779, incorporated herein by reference in itsentirety, and/or efficiency improvement amplifiers such as envelopetracking amplifiers, as described in U.S. patent application Ser. No.13/829,946, incorporated herein by reference in its entirety.Furthermore, the various series connected amplifiers may further becoupled via impedance matching and/or harmonic termination networks, asdescribed in, for example, U.S. patent application Ser. No. 13/967,866and U.S. patent application Ser. No. 13/797,686, both incorporatedherein by reference in their entirety. The amplifier module (130) thusfeeds an amplified RF signal of the amplifier module (120) to theduplexer unit (130), which duplexer unit further filters the RF signalto be transmitted through a band-pass filter centered at a frequency ofoperation of the band within which the RF signal is transmitted. Theduplexer unit (130) can allow simultaneous transmit and receive via asame transmit/receive port, such as the antenna (110), by filtering thetransmit RF signal such as not to affect (e.g. overload) a receive RFsignal to the receive path and filtering a receive RF signal accordingto a receive frequency band and channel. A received RF signal,subsequent to filtering by the duplexer (130), can be fed to thetransceiver unit (140) via an internal amplifier (e.g. low noiseamplifier) which is tuned for the frequency of the received RF signaland has an input stage closely matched to the receive path electricalcharacteristics (e.g. impedance) at the tuned frequency. Once thereceived RF signal is amplified, the transceiver unit (140) can furtherdown convert the received amplified signal to an intermediate frequency(IF) signal used for decoding of the information (e.g. voice, data) inthe received RF signal.

FIG. 2A shows an exemplary graph of frequency spectra of an RF transmitsignal (210) and an RF receive signal (220) of the transmit/receivesystem (100) of FIG. 1. The transmit RF signal has an RF spectrum (210)centered at a transmit center frequency f1 _(T) and of peak power P_(T)at the transmit center frequency. Similarly, the receive RF signal hasan RF spectrum (220) centered at a receive center frequency fl_(R) andof peak power P_(R) at the receive center frequency. As depicted in theexemplary graph of FIG. 2A, the transmit RF signal can have an energyseveral order of magnitude higher than the energy of the receive RFsignal, such as, for example, P_(T)/P_(R)>100. The separation betweenthe receive and the transmit channels in correspondence of the receiveand transmit signals, as measured for example by the difference betweenf1 _(T) and f1 _(R), and in combination with the filters of the duplexerunit (130) of FIG. 1, allow for a detection of the RF receive signal.Therefore, design of the duplexer (130) can be according to a desiredtransmit/receive channel separation, latter channel separation takinginto consideration spread in frequency required for the specificmodulation scheme used in the RF transmit/receive signal.

As previously mentioned, a transmit/receive RF signal can be incorrespondence of a frequency band associated to a wireless standard(e.g. mode), and in turn, the frequency band can comprise a plurality ofchannels which can be used to transmit/receive an RF signal accordingthe defined modulation scheme of the wireless standard. FIG. 2B showstwo adjacent bands (230) and (240), each band comprising a plurality(e.g. 3) of adjacent channels with center frequencies (f1 _(R), f2 _(R),f3 _(R)) for the channels of band (230) and center frequencies (f1 _(T),f2 _(T), f3 _(T)) for the channels of band (240). Separation of thevarious channels (e.g. distance between two adjacent center frequencies)can be such as to allow a frequency spread defined by the attendingmodulation scheme. The bands (230, 240) shown in FIG. 21 can be used forthe transmit/receive system (100) of FIG. 1, such as for example, band(230) for receiving and band (240) for transmitting. Accordingly, thetransmit/receive system can use any of the three channels of band 230)for transmitting and any of the three channels of band (240) forreceiving. The duplexer unit (130) of the transmit/receive system (100)can be designed such as to have a center frequency for its receivefilter according to the center frequency of the receive band (230) and acenter frequency for its transmit filter according to the centerfrequency of the transmit band (240). As shown in the exemplary graph ofFIG. 2B, at a given time of operation of the transmit receive system(100), a transmit channel defined by the center frequency f1 _(T) can beused simultaneously with a receive channel defined by the centerfrequency f3 _(R), and at another time of operation as depicted by FIG.2C, a transmit channel defined by the center frequency f2 _(T) can beused simultaneously with a receive channel defined by the centerfrequency f2 _(R). In some cases the spacing (e.g. frequency spread)between the transmit and receive channels can be kept constant, such as,for example, exclusively using the pairs (f1 _(T), f1 _(R)), (f2 _(T),f2 _(R)) or (f3 _(T), f3 _(R)) as transmit/receive frequency centers. Asdepicted by the two FIGS. 2B and 2C, the further apart the two channelsused for transmit and receive, the least the interference between thetransmit and receive signals can be. As the RF transmit signal can havefar more energy than that of an RF receive signal, interference of thetransmit RF signal into the receive path can have a noticeable effect onreception of the receive RF signal (e.g. overload of the receive path).Therefore, one can minimize such interference effect by increasing thereceive/transmit channel spacing, or by not using all possiblecombinations transmit/receive channels (e.g. constant spacing as perabove), both at the cost of reduced number of channels for a givenfrequency band of operation. Alternatively and according to the variousembodiments of the present disclosure, filtering can be used to furtherreduce the amount of transmit RF signal reaching the receiver.

According to an embodiment of the present disclosure, a method forreducing such interference effect while maintaining a higher number oftransmit/receive channels is provided. Such method uses a tunable filterin the receive and/or transmit path to further immune the two paths withrespect to each other. For example, a tunable band-reject filter tunedat a center frequency of an RF transmit signal (e.g. f1 _(T), f2 _(T),f3 _(T)) can be placed in the receive path to reject a transmit RFfrequency in the receive path such as depicted in FIG. 2D. Such tunableband-reject filter (235) of FIG. 2D can be placed after the duplexerunit (130) (e.g. between duplexer and input amplifier of transceiver140) and can be designed to provide band-reject filters centered at anyone of the frequencies (f1 _(T), f2 _(T), f3 _(T)) of the channels usedin the transmission of the RF signal. Although not shown in theexemplary embodiment of FIG. 21), the tunable band reject filter cancomprise one or more stages (e.g. resistor-inductor-capacitor RLC)interconnected in a series and/or a shunt configuration and coupledand/or connected to the receive path in a series and/or shuntconfiguration (shunt configuration not shown in FIG. 2D). Some examplesof such filters are provided in the above mentioned U.S. applicationSer. No. ______ entitled “Integrated Tunable Filter Architecture”(Attorney Docket No. PER-115-PAP) filed on even date herewith andincorporated herein by reference in its entirety. A controller unitaware of the operation of the transmit/receive system of FIG. 2D, suchas, for example, the transceiver unit (140), can control theconfiguration of the tunable band-reject filter (235) according to thechannel (e.g. a corresponding frequency of operation) being used fortransmission and/or reception at a given time of operation of thesystem. A band-reject filter configuration of the tunable band-rejectfilter (235) of FIG. 2D can reject a frequency within a transmissionchannel while pass frequencies outside the transmission channel. Thistunable notch filter (e.g. band-reject) can be used to reduce theattenuation requirements of the duplexer. Since the controller knows thefrequency assignments (e.g. channels used) at that moment, it can placethe center of the notch at the appropriate frequency. The designrequirements for such notch filter may be easier than designrequirements of a bandpass filter or the duplexer filter. Fewerresonators may be required because the filter doesn't have to cover theentire band (e.g. consisting of various channels) and the shape of thefilter response can be less important than the shape of a bandpassand/or duplexer filter. The reduced number of resonators (e.g. filterstages) typically results in lower insertion loss (e.g. less than 1.5 dBversus larger than 2.0 dB) and smaller physical implementations of suchtunable notch filter.

The person skilled in the art readily knows that the system blockdiagram depicted in FIG. 1 is a simplistic representation of a singlepath transmit/receive system used in an RF front-end stage, as suchfront-end stage can include a plurality of similar transmit/receivepaths sharing the same antenna (110), and the same transceiver unit(140). In other exemplary configurations, the plurality of thetransmit/receive paths can use different antennas, such as to furtherincrease data throughput via simultaneous RF transmit/receive on a sameor different bands and/or channels, as depicted in FIG. 3. Some examplesof such system implementations using a plurality of transmit/receivepaths and antennas are carrier aggregation, multiple-inputmultiple-output (MIMO), or simply multiple radios in one end productsuch as a mobile cell phone.

With further reference to FIG. 3, a block diagram of a multiple paths(e.g. two paths) transmit/receive system (300) is shown, wherein eachtransmit/receive path uses a separate antenna. Principle of operation ofeach of the two transmit/receive paths is the same as described inrelation to the block diagram depicted in the FIG. 1. A firsttransmit/receive path of the system (300) of FIG. 2 is defined by thetransceiver unit (140), the amplifier module (120), the duplexer unit(130) and the antenna (110), whereas a second transmit/receive path ofthe system (300) is defined by the transceiver unit (140), the amplifiermodule (320), the duplexer unit (330) and the antenna (310). It shouldbe noted that the antenna (110, 130) can be considered as a commontransmit/receive port for the corresponding transmit/receive path asother types of ports can be envisioned such as to allow simultaneousoutflow and inflow of signals to the transmit/receive system 300, suchas, for example, a coupler and/or other devices known to the skilledperson. It should further be noted that although the exemplary multipleRF paths transmit/receive system (300)) of FIG. 3 uses a singletransceiver unit (140) for all transmit/receive paths, according to someembodiments, different transceiver units can be used for each of theplurality of transmit/receive paths or for groups of the plurality oftransmit/receive paths.

The duplexer units (130) and (330) of FIG. 3 can be designed for certaintransmit/receive frequency bands of operation. As previously mentioned,transmit/receive system (140, 120, 130, 110) can transmit at a firsttransmit band and receive at a first receive band, whereastransmit/receive system (140, 320, 330, 310) can transmit at a secondtransmit band and receive at a second receive band. In some cases, thefirst and second transmit/receive bands can be a same band (e.g. samefrequency span) and in other cases they can be different, as theconfiguration depicted in FIG. 3 can allow increased in data throughputby using the multiple (e.g. two) transmit/receive paths for an aggregatetransmit/receive scheme (e.g. of a same mode) or by using the multipletransmit/receive paths for transmit/receive different modes.

FIG. 4A shows a frequency plan that can be used by the multiple RF pathstransmit/receive system (300) of FIG. 3 to increase data throughput. Inthe frequency plan depicted in FIG. 4A, a first frequency band (410) canrange from a frequency f₁ to a frequency f₂, while a second frequencyband (420), adjacent to the frequency band (410), can range from thefrequency f₂ to a frequency f₃. Similarly, at a far end side of thefrequency plan of FIG. 4A, a frequency band (430) can range from afrequency f₄ to a frequency f₅, while an adjacent frequency band (440),can range from the frequency f₅ to a frequency f₆. Within the frequencyband (410, 420, 430, 440), a first channel (410 a. 420 a. 430 a, 440 a)may be adjacent to a second channel (410 b, 420 b. 430 b. 440 b), whilea third channel (410 f. 4201, 430 f, 440 f) may be separated from thefirst and the second channels.

In a first mode of operation of the multiple RF paths transmit/receivesystem (300) of FIG. 3 and with reference to the frequency plan of FIG.4A, a mode being defined by, for example, a wireless system standard,separate frequency bands can be used by the multiple transmit/receivepaths of the multiple RF paths transmit/receive system (300) for eachsignal transmission and signal reception. For example, any channel (410a, 410 b, . . . , 410 f) of frequency band (410) can be used forreception of an RF signal via the transmit/receive system (140, 120,130, 110) while any channel (430 a, 430 b, . . . , 430 f) of frequencyband (430) can be used for reception of an RF signal via thetransmit/receive system (140, 320, 330, 310). Similarly and simultaneousto the reception, any channel (420 a. 420 b, . . . , 420 f) of frequencyband (420) can be used for transmission of an RF signal via thetransmit/receive system (140, 120, 130, 110) while any channel (440 a,440 b, . . . , 440 f) of frequency band (440) can be used for receptionof an RF signal via the transmit/receive system (140, 320, 330, 310). Insuch mode of operation of the multiple RF paths transmit/receive system(300) of FIG. 3, transmission over the band (420) by one of thetransmit/receive systems of the multiple RF paths system (300) cancoincide with transmission and/or reception over the bands (430, 440) bythe other transmit/receive system, and similarly, transmission over theband (440) by one transmit/receive system of the multiple RF pathssystem (300) can also coincide with transmission and/or reception overthe bands (410, 420) by the other transmit/receive system. Therefore,during operation of the multiple RF paths transmit/receive system (300)of FIG. 3, an exemplary spectrum occupied by each of thetransmit/receive systems of the multiple RF paths system (300) can berepresented by the graphs depicted in FIGS. 2B and 2C, wherein thefrequency bands (230, 240) can be (410, 420) for the transmit/receivesystem (140, 120, 130, 110) or (430, 440) for the transmit/receivesystem (140, 320, 330, 310).

According to a second mode of operation of the multiple RF pathstransmit/receive system (300)) of FIG. 3 and with reference to thefrequency plan of FIG. 4A, a mode being defined by, for example, awireless system standard, a same frequency band can be used by themultiple transmit/receive paths of the multiple RF pathstransmit/receive system (300) for each signal transmission and signalreception. For example, any channel (410 a, 410 b, . . . , 410 f) offrequency hand (410) can be used for reception of an RF signal via thetransmit/receive system (140, 120, 130, 110) while the same channels(410 a, 410 b, . . . , 410 f) of frequency band (410) can be used forreception of an RF signal via the transmit/receive system (140, 320,330, 310). Similarly and simultaneous to the reception, any channel (420a, 420 b, . . . , 420 f) of frequency band (420) can be used fortransmission of an RF signal via the transmit/receive system (140, 120,130, 110) while any channel (420 a, 420 b, . . . , 420 f) of the samefrequency band (420) can be used for reception of an RF signal via thetransmit/receive system (140, 320, 330, 310). In such mode of operationof the multiple RF paths transmit/receive system (300) of FIG. 3,transmission by one of the transmit/receipt systems of system (300) overthe band (420) can coincide with transmission and/or reception over thebands (410, 420) by the other transmit/receive system, and similarly,transmission over the band (440) by one transmit/receive system of themultiple RF paths system (300) can also coincide with transmissionand/or reception over the bands (430, 440) by the other transmit/receivesystem of the multiple RF paths system (300). Therefore, duringoperation of the multiple RF paths transmit/receive system (300) of FIG.3, a spectrum occupied by each of the transmit/receive systems of themultiple RF paths system (300) can be represented by the graphs depictedin FIGS. 2B and 2C, wherein the frequency bands (230, 240) can be either(410, 420) for both transmit/receive systems (140, 120, 130, 110) and(140, 320, 330, 310), or (430, 440) for both the transmit/receivesystems (140, 120, 130, 110) and (140, 320, 330, 310).

According to an embodiment of the present disclosure, a tunable notchfilter, such as a narrow tunable band-reject filter, can be placed (e.g.via a series and/or a shunt connection/coupling, such as depicted inFIG. 6 later described) in either or both transmit/receive systems (140,120, 130, 110) and (140, 320, 330, 310) in order to immune the twosystems from interfering with each other (as depicted for example inFIG. 5A and FIG. 5B later described). As it is known to the personskilled in the art, RF signals at different frequencies used within asame system, such as in the multiple RF paths transceiver/receive system(300) of FIG. 3 operating in either first or second mode of operation asdescribed in the prior sections, can influence each other via, forexample, coupling (e.g. via radiation and/or crosstalk) and/orintermodulation (e.g. intermodulation distortion).

As it is well known to the person skilled in the art, intermodulationbetween two signals at differing frequencies (f₁, f₂) can engendersideband signals centered around each of the frequencies and distantfrom each frequency by the difference of the frequencies (f₁, f₂), asdepicted in FIG. 4B. As shown in the FIG. 4B, two signals (e.g. RFsignals) centered at frequencies (f₁, f₂) with frequency spectra (401)and (402) respectively, can engender intermodulation components (403,404) centered at frequencies (2*f₁−f₂) and (2*f₂−f₁). Let's consider themultiple RF paths transmit/receive system (300) of FIG. 3 operating inthe second mode as described above, wherein both transceiver/receivesystems transmit and receive using a same band. FIG. 4C depicts thetransmit spectrum (401/402) of the first/second transmit/receive systemoperating within a transmit band (420) (e.g. referring to FIG. 4A) andusing a corresponding transmit channel of center frequency f1 _(T)/f3_(T) (e.g. channels 420 a. 420 b of FIG. 4A). Such operation of themultiple RF paths transmit/receive system (300) can engenderintermodulation components (403/404). In particular and as depicted byFIG. 4C and with further reference to FIG. 4A, such intermodulationcomponents can occur within an adjacent reception band (410) andtherefore can affect reception over one or more reception channels ofthe reception band (410) used by the multiple RF paths transmit/receivesystem (300)) as depicted by the receive spectrum (408) of the receiveband (410) in FIG. 4D. Presence (or not) of intermodulation and locationwithin a frequency spectrum can be predicted based on the operation modeof the multiple RF paths transmit/receive system (300). According to thevarious embodiments of the present disclosure, a tunable notch filtercan be used to decrease the signal level at the frequency f₁ and/or atthe frequency f₂, thus reducing the amplitude of the intermodulationproduct (e.g. filter 535 of FIG. 6 later described), or the notch can beused to attenuate the intermodulation product (e.g. filter 545 a of FIG.6 later described) that is generated (e.g. 2*f₂−f₁). Such decrease ofintermodulation distortion can effectively counter the limiting effectof the intermodulation on the performance of a radio system (e.g. system300 of FIG. 3).

The teachings according to the present disclosure provide methods andapparatus to reduce such interference in a multiple RF pathstransmit/receive system, such as the exemplary system depicted in FIG.3. It follows, that according to an exemplary embodiment of the presentdisclosure, a tunable notch filter, such as for example a tunable narrowband-reject filter tuned at a center frequency of an RF transmit signal,can be used in a transmit/receive system to immune such system from asecond transmit/receive system operating at a different RF transmitfrequency. This is depicted in FIG. 5A, wherein a tunable notch filter(535) is used in a multiple RF paths transmit/receive system (500),similar to the system (300) of FIG. 3, such as to immune atransmit/receive system (140, 320, 330, 310) from the transmit/receivesystem (140, 120, 130, 110). In the embodiment according to the presentdisclosure as depicted in FIG. 5A, the tunable notch filter (535) placed(e.g. in series connection) between the antenna (310) and the duplexer(330) of the transmit/receive system (140, 320, 330, 310) can be tunedto a frequency of operation of the transmit/receive system (140, 120,130, 110), such as for example, an RF transmit frequency. According toother embodiments of the present disclosure, the tunable notch filter(535) can be placed at any point of the transmit/receive path betweenthe transceiver unit (140) and the antenna (310), and can be connectedin either a series or a shunted configuration to the transmit/receivepath, the connection type being dependent on the design of the tunablenotch filter used. According to yet further embodiments of the presentdisclosure, one or more tunable notch filter similar to the tunablenotch filter (535) can be placed at any point of the transmit/receivesystem (140, 320, 330, 310) between the transceiver unit (140) and theantenna (310). According to yet another embodiment of the presentdisclosure, a filter of the tunable notch filter (535) of FIG. 5A can bea narrow band-reject filter which rejects a frequency within a firsttransmission channel used by the transmit/receive system (140, 120, 130,110) while passes frequencies outside the first transmission channel andtherefore can allow the transmit/receive system (140, 320, 330, 310) touse a transmission channel or reception channel adjacent to the firsttransmission channel, and thereby increase a total data (RF) throughputof system (500).

It should be noted that when the exact same bands (e.g. transmit band)are being used in both transmit/receive systems (e.g. as per system 500of FIG. 5A), a duplexer of one transmit/receive system can protect itsreceiver from its transmitter as well as the second transmitter.However, in the case where the second transmitter operates at otherbands (e.g. different from one used by the first transmitter), theduplexer may not have sufficient attenuation at those bands andtherefore cannot protect its receiver from the second transmitter.Furthermore transmitter nonlinearity can generate increased modulatedspectral bandwidth and harmonics not sufficiently attenuated by thecorresponding duplexer filter and which can be detrimental to the otherreceiver. It follows that according to the various embodiments of thepresent disclosure, the notch filter (e.g. 535) may be in the portion ofthe transmit path preceding the duplexer (e.g. 330) as depicted in FIG.5B, or in the common transmit/receive path between the duplexer andantenna as depicted in FIG. 5A. The person skilled in the art readilyknows that such problems as related to isolation of transmit signals aremore pronounced when the two radio paths (e.g. (140, 120, 130, 110) and(140, 320, 330, 310) are in one small area such as a mobile phone, whereisolation between the antennas (110, 310) may be quite limited (e.g. 15dB of isolation) and therefore a transmitted signal from one antenna caninfluence quality of reception over the other antenna. In the embodimentdepicted by FIG. 511, the notch filter (535) can be tuned at a centerfrequency corresponding to a harmonic of the operating frequency of theRF signal amplified by (320).

Although the exemplary configuration depicted by FIGS. 5A-5B show onetunable notch filter in the bottom transmit/receive system, according toan embodiment of the present disclosure, one or more tunable notchfilters (e.g. 545 a, 545 b) similar to the tunable notch filter (535)can be placed (e.g. via a series and/or a shunt connection) at any pointof the transmit/receive system (140, 120, 130, 110) as depicted, forexample, in FIG. 6. In the exemplary embodiment according to the presentdisclosure depicted in FIG. 6, the tunable notch filter (545 a) isshunted to the receive path of the transmit/receive system (140, 120,130, 110), whereas the tunable notch filter (545 b) is in seriesconnection between the antenna (110) and the duplexer unit (130). Theexemplary embodiment according to the present disclosure as depicted inFIG. 6 can immune from interference either transmit/receive system fromthe other. Tunable notch filters (545 a, 545 b) can be tuned to reduceeffect of the frequency spectrum used in the transmit/receive system(140, 320, 330, 310) on the frequency spectrum used in thetransmit/receive system (140, 120, 130, 110) similar to the way thattunable notch filter (535) can reduce effect of the frequency spectrumused in the transmit/receive system (140, 120, 130, 110) on thefrequency spectrum used in the transmit/receive system (140, 320, 330,310).

In the embodiment according to the present disclosure as depicted inFIG. 6, the various tunable notch filters (535, 545 a, 545 b) can becontrolled via a controller unit aware of the operation of eachtransmit/receive system (140, 120, 130, 110) and (140, 320, 330, 310),such as the transceiver unit (140). Depending on a mode of operation(e.g. modulation, frequency) of each of the transmit/receive systems,the controller unit can know how to tune a tunable notch filter in orderto immune each of the transmit/receive systems from interference of theother. In some cases, it is possible that no tunable notch filter isnecessary, and therefore, according to some embodiments of the presentdisclosure, the tunable notch filter can be switched in or out of acorresponding path, such as depicted in FIG. 7, wherein RF switches (725a, 725 b, 725 c) can be used to switch in or out tunable notch filters(545 a, 545 b, 535).

According to a further embodiment of the present disclosure, thecombination of tunable notch filter (e.g. 545 a, 545 b, 535) and switch(e.g. (725 a-c) can be monolithically integrated within a sameintegrated circuit as depicted in FIG. 8A and FIG. 8B. The integratedcircuit of FIG. 8A/SB comprises a control terminal (CNTRL) which can beused to control the configuration of the internal switch (725 c/725 a)and the tuning of the tunable notch filter (535/545 a) via a controlsignal, generated, for example, by a transceiver unit or a signal-awarecontroller module. The person skilled in the art will know that suchcontrol signal can comprise one or more digital and/or analog signallines and a corresponding interface can be implemented in a variety ofmethods which are outside the scope of the present disclosure. As notedin the previous sections of the present disclosure, the integratedcircuit of FIG. 8A can be used in a series connection with a signal pathconnected to ports S₁ and S₂ of the integrated circuit, whereas theintegrated circuit of FIG. 8B can be used in a shunt connection with asignal path connected to port S (or port N) of the integrated circuitand a common reference potential connected to the port N (or port S) ofthe integrated circuit. In both configurations of the integrated circuitdepicted by FIG. 8A and FIG. 8B, the turning ON/OFF of the switch cancause a current to flow nor not through the tunable notch filter andtherefore affect or not a characteristic of a signal coupled to theintegrated circuit. Furthermore, such integrated circuit as depicted inFIG. 8A and FIG. 8B can be made to operate in a single-ended ordifferential signal mode, as required by a receive/transmit path whereinsuch integrated circuit is used. As known by the person skilled in theart, a receive path of a multiple RF paths transmit/receive system suchas one depicted in the various figures of the present disclosure cancomprise a differential signal path (e.g. input to a transceiver unit).

The tunable notch filters described in the various embodiments accordingto the present disclosure can be constructed using one or more variablereactive elements, such as variable capacitors and variable inductors.Digitally tunable capacitors (DTC) and/or digitally tunable inductors,as described in, for example. International Application No.PCT/US2009/001358 and U.S. patent application Ser. No. 13/595,893, canalso be used in constructing such tunable notch filter. The personskilled in the art readily knows how to realize such tunable filters andhow to select components with values (e.g. ranges of values) consistentwith a desired tilter bandwidth and attenuation. As known by the personskilled in the art, such components can be partitioned into variousfilter stages via series and/or shunt connections, and in turn, thevarious filter stages can be interconnected (e.g. cascaded) via seriesand/or shunt connections. Some exemplary embodiments of tunable notchfilters are described in the above mentioned U.S. application Ser. No.______ entitled “Integrated Tunable Filter Architecture” (AttorneyDocket No. PER-115-PAP) filed on even date herewith and incorporatedherein by reference in its entirety.

Although the various exemplary embodiments of the present disclosure arebased on a multi-path transmit/receive system showing two separatetransmit/receive systems (e.g. (140, 120, 130, 110) and (140, 320, 330,310)), each with a dedicated transmit/receive antenna (e.g. (110, 310),such limitation of two transmit/receive systems is mainly exemplary innature and not intended to limit the scope of the invention which cancertainly be extended to more than two such transmit/receive systems,each with a dedicated transmit/receive antenna. In such configuration, acontroller unit can tune the various tunable notch filters according tothe known signal spectra used in the various transmit/receive systems.Such spectra can comprise not only known operating frequencies (e.g.channel frequencies) associated to the various transmitted and receivedsignals within the various transmit/receive systems, but also cancomprise various harmonics and intermodulation products thereof whichalone or in combination can affect operation of one or more of thevarious transmit/receive systems. Additionally, each transmit/receivesystem can comprise more than one transmit/receive path, as a pluralityof parallel transmit/receive paths can be connected to an antenna via adedicated antenna switch, as typically done in current RF front-endstages used in current cellular devices.

By way of further example and not limitation, any switch or switchingcircuitry of the present disclosure, such as switches (725 a-c) of FIG.7 can be implemented using transistors, stacked transistors (FETs),diodes, or any other devices or techniques known to or which can beenvisioned by a person skilled in the art. In particular, such switchingcircuitry can be constructed using CMOS technology and variousarchitectures known to the skilled person, such as, for example,architecture presented in U.S. Pat. No. 7,910,993, issued on Mar. 22,2011 and entitled “Method and Apparatus for use in Improving Linearityof MOSFET's using an Accumulated Charge Sink”, and in U.S. Pat. No.6,804,502, issued on Oct. 12, 2004 and entitled “Switch Circuit andMethod of Switching Radio Frequency Signals”, both incorporated hereinby reference in their entirety. FIG. 9 shows an exemplary embodiment ofa single-pole single-throw switch with stacked transistors, which theskilled person can use as an elementary component of the variousswitches used in the various embodiments according to the presentdisclosure.

Although FETs (e.g. MOSFETs) can be used to describe transistor andstacked transistor switches used in the various embodiments of thepresent disclosure, a person skilled in the art would recognize thateither P-type or N-type MOSFETs may be used. The skilled person wouldalso recognize that other types of transistors such as, for example,bipolar junction transistors (BJTs) can be used instead or incombination with the N-type or P-type MOSFETs. Furthermore, a personskilled in the art will also appreciate the advantage of stacking morethan two transistors, such as three, four, five or more, provide on thevoltage handling performance of the switch. This can for example beachieved when using non bulk-Silicon technology, such as insulatedSilicon on Sapphire (SOS) technology and silicon on insulated (SOI)technology. In general, the various switches used in the variousembodiments of the present disclosure, including when monolithicallyintegrated with a tunable notch filter, such as depicted in FIG. 8, canbe constructed using CMOS, silicon germanium (SiGe), gallium arsenide(GaAs), gallium nitride (GaN), bipolar transistors, or any other viablesemiconductor technology and architecture known, includingmicro-electro-mechanical (MEM) systems. Additionally, different devicesizes and types can be used within a stacked transistor switch such asto accommodate various current handling capabilities of the switch.

The examples set forth above are provided to give those of ordinaryskill in the art a complete disclosure and description of how to makeand use the embodiments of the present disclosure, and are not intendedto limit the scope of what the inventors regard as their disclosure.Modifications of the above described modes for carrying out thedisclosure may be used by persons of skill in the art, and are intendedto be within the scope of the following claims. All patents andpublications mentioned in the specification may be indicative of thelevels of skill of those skilled in the art to which the disclosurepertains. All references cited in this disclosure are incorporated byreference to the same extent as if each reference had been incorporatedby reference in its entirety individually.

It is to be understood that the disclosure is not limited to particularmethods or systems, which can, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. As used in this specification and the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontent clearly dictates otherwise. The term “plurality” includes two ormore referents unless the content clearly dictates otherwise. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which the disclosure pertains.

A number of embodiments of the disclosure have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the presentdisclosure. Accordingly, other embodiments are within the scope of thefollowing claims.

1. A radio frequency (RF) circuital arrangement comprising: a firsttransmit/receive system comprising a first transmit path configured totransmit a first transmit RF signal at a first transmit/receive port,and a first receive path configured to receive a first receive RF signalat the first transmit/receive port; a second transmit/receive systemcomprising a second transmit path configured to transmit a secondtransmit RF signal at a second transmit/receive port, and a secondreceive path configured to receive a second receive RF signal at thesecond transmit/receive port, and one or more tunable notch filtersconfigured to reduce a radio frequency interference of atransmit/receive system of the first and second transmit/receive systemsover the other transmit/receive system.
 2. The RF circuital arrangementof claim 1, wherein a tunable notch filter of the one or more tunablenotch filters is connected between a transmit/receive port of the firstand the second transmit/receive ports and a duplexer unit incorrespondence of the transmit/receive port.
 3. The RF circuitalarrangement of claim 1, wherein a tunable notch filter of the one ormore tunable notch filters is connected between a duplexer unit of atransmit/receive system of the first and the second transmit/receivesystems and an input RF amplifier of the transmit/receive system.
 4. TheRF circuital arrangement of claim 1, wherein the tunable notch filter ofthe one or more tunable notch filters is connected between a transmitamplifier of a transmit/receive system of the first and the secondtransmit/receive systems and a duplexer unit in correspondence of thetransmit/receive system.
 5. The RF circuital arrangement of any one ofclaims 2-4, wherein the tunable notch filter is connected in a seriesand/or a shunt configuration.
 6. The RF circuital arrangement of claim1, further comprising one or more RF switches, wherein the one or moreRF switches are configured to enable and/or disable an effect of the oneor more tunable notch filters over a transmit/receive system of thefirst and second transmit/receive systems.
 7. The RF circuitalarrangement of claim 6, wherein a switch of the one or more RF switchesis connected in parallel to a tunable notch filter of the one or moretunable notch filters.
 8. The RF circuital arrangement of claim 7,wherein the switch is connected between a first and a secondinput/output terminal of the tunable notch filter.
 9. The RF circuitalarrangement of claim 6, wherein a switch of the one or more switches isconnected in series to a tunable notch filter of the one or more tunablenotch filters.
 10. The RF circuital arrangement of claim 7 or claim 9,wherein a switch of the one or more switches comprises stackedtransistors.
 11. The RF circuital arrangement of claim 1, wherein atunable notch filter of the one or more tunable notch filters is aband-reject filter configured to reject a frequency band incorrespondence of a first transmit/receive channel and to pass afrequency band in correspondence of a second transmit/receive channeladjacent to the first transmit/receive channel.
 12. The RF circuitalarrangement of claim 11, wherein the frequency band is in correspondenceof one of: a) a frequency of operation of a transmit RF signal of thefirst and the second transmit RF signals, b) a harmonic of a), and c) anintermodulation product of any combination of a) and b).
 13. The RFcircuital arrangement of claim 1, wherein a tunable notch filter of theone or more tunable notch filters comprises one or more variablereactive elements.
 14. The RF circuital arrangement of claim 13, whereinthe one or more variable reactive elements are partitioned in one ormore stages interconnected via series and/or shunt connections.
 15. TheRF circuital arrangement of claim 13, wherein a reactive element of theone or more variable reactive elements comprises one of: a) a digitallytunable capacitor, and b) a digitally tunable inductor.
 16. The RFcircuital arrangement of claim 1, wherein during operation of thecircuital arrangement, the first and the second transmit/receive systemsare adapted to simultaneously transmit and/or receive an RF signal overa channel of a plurality of channels of a frequency band.
 17. The RFcircuital arrangement of claim 1, wherein the first transmit/receiveport comprises a first transmit/receive antenna and the secondtransmit/receive port comprises a second transmit/receive antenna. 18.The RF circuital arrangement of claim 1, further comprising one or moretransmit/receive systems similar to the first/second transmit/receivesystems, wherein one or more of the one or more tunable notch filtersare configured to reduce a radio frequency interference of atransmit/receive system of the RF circuital arrangement over the othertransmit/receive systems of the RF circuital arrangement.
 19. A radiofrequency (RF) integrated circuit comprising: an RF switch comprising afirst switch terminal and a second switch terminal; a RF tunable notchfilter comprising a first port and a second port, wherein in a firstconfiguration of the RF integrated circuit the first port is connectedto the first switch terminal and the second port is connected to thesecond switch terminal, and in a second configuration of the RFintegrated circuit the first port is connected to the second switchterminal; a first input/output terminal connected to the first switchterminal; a second input/output terminal connected to the second port;and a control terminal, wherein during operation, a control signal atthe control terminal of the RF integrated circuit is configured to tunethe RF tunable notch filter and/or control the RF switch toenable/disable a current flow through the RF tunable notch filter. 20.The RF integrated circuit of claim 19, wherein the RF tunable notchfilter comprises one or more variable reactive elements.
 21. The RFintegrated circuit of claim 20, wherein a reactive element of the one ormore variable reactive elements comprises one of: a) a digitally tunablecapacitor, and b) a digitally tunable inductor.
 22. The RF integratedcircuit of claim 19 monolithically integrated on a same integratedcircuit.
 23. The RF integrated circuit of claim 22 fabricated using atechnology comprising one of: a) Silicon on Sapphire, b) Silicon onInsulator, c) bulk-Silicon, and d) micro-electro-mechanical systems. 24.The RF circuital arrangement of claim 19 configured for operation in oneof: a) a differential mode, and b) single-ended mode.
 25. Acommunication device for transmitting and receiving RF signals via oneor more antennas, the communication device comprising the RF circuitalarrangement of claim 1 or claim 18, wherein the one or more antennas ofthe communication device are coupled to a plurality of transmit/receiveports of a plurality of transmit/receive systems of the RF circuitalarrangement.
 26. The communication device of claim 25 further comprisinga transceiver unit, wherein during operation of the communicationdevice, the transceiver unit is adapted to send/receive a plurality oftransmit/receive RF signals to/from the plurality of transmit/receivesystems of the RF circuital arrangement.
 27. The communication device ofclaim 26, wherein, during operation of the communication device, thetransceiver unit is adapted to control the one or more tunable notchfilters based on a characteristic of one or more RF signals of theplurality of transmit/receive RF signals.
 28. The communication deviceof claim 27, wherein the characteristic comprises a frequency spectra ofthe one or more RF signals.
 29. The communication device of claim 28,wherein the frequency spectra comprises at least one of: a) spectra of afrequency of operation of an RF signal of the one or more RF signals, b)spectra of a harmonic of a) and c) spectra of an intermodulation productof the one or more RF signals.
 30. A method for reducing radio frequency(RF) interference in an RF circuital arrangement, the method comprising:providing a plurality of RP transmit/receive systems coupled to aplurality RF antennas; connecting in a path of a first RFtransmit/receive system of the plurality of RF transmit/receive systemsone or more RF tunable notch filters; adjusting an RF tunable notchfilter of the one or more RF tunable notch filters based on acharacteristic of a transmit/receive RF signal of an RF transmit/receivesystem of the plurality of RF transmit/receive systems other than thefirst RF transmit/receive system; and based on the adjusting, reducingan RF interference of the transmit/receive RF signal over the first RFtransmit/receive system.
 31. The method of claim 30, further comprising:monitoring the characteristic of the transmit/receive RF signal; basedon the monitoring, detecting a change of the characteristic; based onthe detecting, further adjusting the RF tunable notch filter; and basedon the further adjusting, maintaining a reduced RF interference of thetransmit/receive RF signal over the first RF transmit/receive system.32. The method of claim 31, further comprising: based on themaintaining, providing a larger operating frequency spectrum to thefirst transmit/receive RF system; based on the providing, increasing anumber of transmit/receive channels available to the firsttransmit/receive RF system; and based on the increasing, increasing datathroughput of the RF circuital arrangement.
 33. The method of claim 30,wherein the characteristic of the transmit/receive RF signal comprises aknown operating frequency of the transmit/receive RF signal.
 34. Themethod of claim 33, wherein the known operating characteristic is incorrespondence of a selected transmit/receive channel.
 35. The method ofclaim 34, wherein selection of the selected transmit/receive channel isperformed by a transceiver unit.
 36. A radio frequency (RF) circuitalarrangement comprising: a transmit path configured to transmit, during atransmit mode of operation of the RF circuital arrangement, a transmitRF signal at a transmit/receive port of the RF circuital arrangement; areceive path configured to receive, during a receive mode of operationof the RF circuital arrangement, a receive RF signal at thetransmit/receive port, and a tunable notch filter configured to reduce aradio frequency interference of the transmit RF signal over the receiveRF signal, wherein during operation, the RF circuital arrangement isconfigured to simultaneously operate in the transmit and receive modesof operation.
 37. The RF circuital arrangement of claim 36, wherein thetransmit path and the receive path are coupled to the transmit/receiveport via a duplexer unit and wherein the tunable notch filter isconnected between the duplexer unit and one of: a) an input RF amplifierof the receive path, b) a transmit RF amplifier of the transmit path,and c) the transmit/receive port.
 38. The RF circuital arrangement ofclaim 36 or claim 37, wherein the tunable notch filter is connected in aseries or shunt configuration.
 39. The RF circuital arrangement of claim38, further comprising an RF switch coupled to the tunable notch filter,wherein during operation of the RF circuital arrangement, the RF switchis configured to enable and/or disable an effect of the tunable notchfilter over the receive RF signal.
 40. The RF circuital arrangement ofclaim 39, wherein the switch comprises stacked transistors.
 41. The RFcircuital arrangement of claim 39, wherein the switch is connected inone of: a) parallel configuration and b) serial configuration to thetunable notch filter.
 42. The RF circuital arrangement of claim 36,wherein the tunable notch filter is a band-reject filter configured,during operation of the RF circuital arrangement, to reject a frequencyof operation of the transmit RF signal and to pass a frequency ofoperation of the receive RF signal.
 43. The RF circuital arrangement ofclaim 42, wherein: the frequency of operation of the transmit RF signalis in correspondence of a transmit channel of a plurality of transmitchannels; the frequency of operation of the receive RF signal is incorrespondence of a receive channel of a plurality of receive channels;and the RF circuital arrangement is configured to operate in one or moretransmit and receive channels.
 44. The RF circuital arrangement of claim36, wherein the tunable notch filter comprises one or more variablereactive elements.
 45. The RF circuital arrangement of claim 44, whereina reactive element of the one or more variable reactive elementscomprises one of: a) a digitally tunable capacitor, and b) a digitallytunable inductor.
 46. The RF circuital arrangement of claim 36, whereinthe transmit/receive port comprises a transmit/receive antenna.
 47. Acommunication device for transmitting and receiving radio frequency (RF)signals via an antenna, the communication device comprising the RFcircuital arrangement of claim 43, wherein the antenna of thecommunication device is coupled to the transmit/receive port of the RFcircuital arrangement.
 48. The communication device of claim 47 furthercomprising a transceiver unit, wherein during operation of thecommunication device, the transceiver unit is configured to send thetransmit RF signal and to receive the receive RF signal respectivelyto/from the transmit path and receive path of the RF circuitalarrangement.
 49. The communication device of claim 48, wherein, duringoperation of the communication device, the transceiver unit is adaptedto control the tunable notch filter based on a transmit channelfrequency and/or a receive channel frequency in correspondence of thetransmit RF signal and the receive RF signal respectively.
 50. A methodfor reducing radio frequency (RF) interference in an RF circuitalarrangement, the method comprising: providing an RF transmit path totransmit a transmit RF signal over an antenna; providing an RF receivepath to receive a receive RF signal over the antenna; coupling a tunablenotch filter to the RF transmit or the RF receive path; adjusting thetunable notch filter based on a frequency of operation of the transmitRF signal; and based on the adjusting, reducing an RF interference ofthe transmit RF signal over the receive RF signal.
 51. The method ofclaim 50, wherein the adjusting further comprises: further adjusting thetunable notch filter based on a frequency of operation of the receive RFsignal.
 52. The method of claim 50, wherein the frequency of operationis in correspondence of a frequency of a selected transmit channel andwherein the adjusting is performed under control of a controller unitaware of the selected transmit channel.
 53. The method of claim 52,wherein the controller unit is a transceiver unit.
 54. The method ofclaim 51, wherein the adjusting is based on an intermodulation productof the frequency of operation of the transmit RF signal and thefrequency of operation of the receive RF signal.